An extranet is a controlled private network that allows access to partners, vendors, suppliers, or an authorized set of customers - normally to a subset of the information accessible from an organization's intranet.

Computer Network Terms II

A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. The connections between nodes are established using either physically wired, optical, or wireless radio-frequency that may be arranged in various network topologies. The best-known computer network is the Internet.